Herbicide



Patented Dec. 18, 1945 I UNITED STATES PATE OFFICE,

. HERBICIDE Colton De Laney, Berkeley; Calif., assignor to California Spray-Chemical Corporation, Rich- 'mond, Calif., a corporation of Delaware No Drawing. Application April 22, 1941,

1 Serial No. 389,748

6 Claims.

This invention relates to an improved her i-. cidal composition of a .type adapted primarily to kill vegetation by means of rootabsorption;

Such herbicides destroy the root systems of plants and sterilize the soil, preynting new seedling growth. Among the desired qualities in such preparations are mobilityand deep penetration within the soil, prolonged effectiveness, and the possibility of eventualrecovery of the'soil to 10 normal condition.

' It is the object ofv my invention to provide a herbicidal composition possessing these qualities in higher degree than in conventional compositions now in use.

It is also the object of'my invention toprovide a herbicide which is noninfiammable and which will render dried vegetation and wood fire resistant.

which isnoncorrosive .to metals and which will render them more resistant to rusting. These properties are obviously important in many of the situations where weed killers are used, for example in lumber yards, around telephone pole-s,

on railroad tracks and around pipe lines.

Among the various preparations which have been used both as soil sterilants and for the pur- A/ further object is to provide a composition Baum, having an alkali-silica ratio of approximately l'to 3.22

'I have found that, in order to obtain a soil sterilant having the improved properties mentioned, the solution as applied to the soil should contain at least 0.4 pound of this sodium silicate 'per 300 square feet of soil treated. I prefer to pose of withering foliage is the well-knownelass utilizing some form of arsenic as the toxic ingredient. It is to this class of preparations that my invention principally relates.

' Briefly stated, I have discovered that arsenical Soil sterilizers are materially improved by the incorporation therein of a quantity of sodium silioate. One effect of the silicate in conjuction-wit'n the arsenic solution is to afford deeper soil penetration of the herbicide. thus making it effective against a wider range of plants than heretofore obtained with conventional arsenic solutions. also increases the amount of available arsenic stored in the soil, decreasing the amount of permanently fixed arsenic and thus makes possible a more nearly normal ultimate recovery of the soil from the arsenical sterilization.

I have found by large scale experience that soils treated with arsenical preparations containing the proper amount of sodium silicate, as more fully discussed below, have remained sterile from two to three times as long as similar soils which.

have been treated with arsenical solutions containing no sodium silicatebut otherwise the same.

The sodium silicate which I ordinarily use in making my improved solution is the ordinary v "N brand{ the gravity of which is about 41" dium hydroxide.

use from 0.5 to 1.0 pound of sodium silicate to 300 square feet of soil; Higher concentrations, up to 4 pounds per 300 square feet, may be used with some quality improvement, but beyond 4 pounds I square feet of soil to be treated is a convenient rate.

The arsenical component of the herbicide may be varied considerably to fit the needs of the individual 'compounder as is well known to those skilled in the art. A common form of arsenical herbicide is that containing sodium arsenite. This is conveniently made by. a water solution of white arsenic (arsenic trioxide, A5203) and sodium hydroxide added varies in practice from about 20 to about 40 parts by weight of NaOH to parts by weight of arsenic trioxide.

My improvement in soil sterilants as applied to a sodium arsenite type herbicide is illustrated by the following general formula:

Parts by weight Arsenic trioxide AszOa At least 8 Sodium hydroxide NaOH At least 2 Water glass, commercial 0.4 to 4.0 Water Variable These ingredients are put into water solution and, for use in the field, any desired quantity of water is used to provide for easy distribution over the soil to be treated. For example, the addition of suflicient water to the above to make 100 parts by weight would give a soil sterilant suitable for field use. If this formula is made with one part by weigh equal to one pound, it would be ef- The relative proportion of 50-- my invention, which has given excellent results:

I Pounds Arsenic trioxide, 99% AS203 51.2 Caustic soda, 50% NaOH 28.5 Sodium-silicate, N brand 3.5 Water a? 16.8

(approx. 6 gal.)

This formula produces a thick syrupy solution which I dilute with water for use. When used in soil sterilization treatment, i. e. to render the soil sterile to plant growth, I prefer to use a solution made by adding suflicient water to each gallon of the concentrate (formula above) to make gallons of solution whichis suitable for treating about 300 square feet of soil surface area. For use as a contact spray to kill annual weeds and top growth of perennial weeds I make about a 1 to 80 dilution. Intermediate dilutions may be desirable in accordance with local conditions.

More water than shownin the above concentrate formula may be used if it is desired to produce aless viscous'stock solution in which case the amount of water subsequently added for the field application may be varied accordingly.

It is to be understood that the kind and concentration of arsenical compounds used ma be variedas desired within the limits necessary to give herbicidal (soil sterilization) properties without losing the benefits derived from the presence of sodium silicate.

readily be adjusted so as to provide a silicate concentrate equivalent to that described above.

I claim: 1. An aqueous herbicidal solution containing:

Parts by weight Arsenic trioxide AS203 At least 8 Sodium hydroxide NaOH At least 2 Water glass, commercial 0.4 to 4.0 Water It is of course not essential that sodium silicate of the above mentioned specification, namely N brand, be used. If other water-glass solutions are used, the proportion inthe mixture can Parts by weight Arsenic trioxide AszOa e At least 8. Sodium hydroxide NaOH At least 2 Water glass, commercial 0.4 to 4.0 5 Water to make 100 2. An aqueous herbicidal solution containing the following in the weight proportions indicated:

Arsenic trioxide, 99% A5203 51.2 Caustic soda, NaOH 28.5 Sodium silicate (water glass) N brand 3.5

3. A herbicide-concentrate consisting of the following in the proportions indicated:

4. The method of treating soil to kill vegetation and prevent new growth therein, comprising wetting such soil with an aqueous solution containing arsenical compounds in herbicidal concentration and sodium silicate.

5. The method of treating soil to kill vegetation and render the soil sterile to plant growth, comprising wetting the soil with an aqueous arsenical solution containing water glass at such rate that the arsenical component is applied in herbicidal amount and the water glass at from 0.4 to 4.0 pounds per 300 square feet of soil surface.

6. The method of treating soil to kill vegetation and prevent new growth therein, comprising wetting such soil with a liquid comprising:

COLTON DE LANEIY. 

